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The amoeba parasite Entamoeba histolytica interacts with the microbiota within the intestine. Enterobacteria are the major source of energy for this parasite. Here, we highlight that the interplay between enterobacteria and E. histolytica is also important for parasite survival during inflammatory stresses and for the success of amoebic infection., (© 2019 John Wiley & Sons Ltd.)

A 1-year-old male red kangaroo (Macropus rufus) with an acute clinical history of lethargy, depression and increased respiratory rate was presented for necropsy examination. Gross lesions in the digestive tract were a distended stomach with watery content and multifocal raised ulcers covered by fibrinous pseudomembranes in the forestomach and caecum. On histopathology, there was necrotizing and ulcerative gastritis and typhlitis with intralesional amoebic trophozoites and Toxoplasma gondii zoites. Lesions due to T. gondii infection were observed in multiple organs and diagnosis was confirmed by fluorescent antibody test and immunohistochemistry. Both toxoplasmosis and gastric amoebiasis are diseases described in macropods. In this case report, we describe concurrent disease caused by both protozoa in a red kangaroo. Lesions of amoebiasis were also observed in the caecum. Both toxoplasmosis and amoebiasis should be considered as differential diagnoses of ulcerative lesions in the gastrointestinal tract in macropods during necropsy examination. Amoebiasis should be suspected especially when ulcerative lesions are observed in the forestomach., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Multiple concurrent infectious processes have previously been reported in the context of advanced HIV with significant immunosuppression. Here we report a case of multiple infections in a 56-year-old man with well-controlled HIV diagnosed 5 years earlier. Soon after returning to Australia following 12 years living in Thailand, he became unwell with fevers, night sweats, arthralgia and myalgia. There were no localising symptoms and examination was unremarkable. Investigations revealed positive syphilis ( Treponema pallidum ) serology with an RPR of 16, a positive urine culture ( Klebsiella pneumoniae ), a pulmonary nodule, a liver abscess and colitis ( Entamoeba histolytica ). Recovery was only complete when all the individual infections were treated., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Ltd (unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.)

Entamoeba histolytica, the causative agent of amoebic colitis and liver abscess in human, ingests the intestinal bacteria and variety of host cells. Phagocytosis of bacteria by the amebic trophozoite has been reported to be important for the virulence of the parasite. Here, we set out to characterize different stages of phagocytosis of type 1 E. coli and investigated the role of a set of amoebic Rab GTPases in the process. The localizations of the Rab GTPases during different stages of the phagocytosis were investigated using laser scanning confocal microscopy and their functional relevance were determined using fluorescence activated cell sorter based assay as well as colony forming unit assay. Our results demonstrate that EhRab7A is localized on the phagosomes and involved in both early and late stages of type 1 E. coli phagocytosis. We further showed that the E. coli or RBC containing phagosomes are distinct from the large endocytic vacuoles in the parasite which are exclusively used to transport human holotransferrin and low density lipoprotein. Remarkably, type 1 E. coli uptake was found to be insensitive to cytochalasin D treatment, suggesting that the initial stage of E. coli phagocytosis is independent of the formation of actin filaments., (© 2016 John Wiley & Sons Ltd.)

Unlabelled: Liver abscess is a serious infection that can cause life-threatening complications., Objective: To describe the epidemiology, diagnosis, and progression of liver abscess at the Dakar National Albert-Royer Children's Hospital., Method: A retrospective study was conducted from over a period of 5 years (1st January 2010 to 31st December 2014). All children aged 0-15 years hospitalized for liver abscess with ultrasound confirmation were included. We collected demographic data (age, gender, socioeconomic status, origin), clinical data (general and hepatic symptoms), diagnostic data (ultrasound, bacteriology) and progression (death, complications, sequelae). The data were analyzed with Epi-info (P<0.05 was considered significant)., Results: We collected 26 cases of liver abscesses, representing a hospital prevalence of 100 cases per 100,000 admissions. Males predominated (sex ratio: 1.36). The children's average age was 7.2 years. Most of the children came from urban areas of Dakar. Low socioeconomic status and precarious lifestyle were the contributing factors. Anemia (69.2%), malnutrition (42.3%), and abdominal trauma (15.3%) were the main causes found. The Fontan triad characteristic of the liver abscess was found in 57.7% of cases. At ultrasound, a single abscess was found in 21 cases. The abscess was located in the right lobe in 18 cases, the left lobe in three cases, and in both lobes in three cases. Segment VI (four cases) was the most frequently involved. Bacteriologically, the abscess was pyogenic in 17 cases and an amoebic abscess in nine cases. The main pyogenic sources found were Klebsiella pneumoniae in two cases, Pseudomonas aeruginosa in one case, Streptococcus pneumoniae in one case, and Staphylococcus aureus in one case. The average duration of antibiotic treatment was 14.5 days. Liver drainage was carried out in 24 cases. The outcome was favorable in all children., Conclusion: The prevalence of liver abscesses at the Albert-Royer Children's Hospital is relatively high, compared to the literature data. Percutaneous drainage combined with antibiotics remains the treatment of choice. The prognosis is favorable., (Copyright © 2016 Elsevier Masson SAS. All rights reserved.)

Background: Entamoeba histolytica, an enteric protozoan parasite, causes amebic colitis and extra intestinal abscesses in millions of inhabitants of endemic areas. E. histolytica completely lacks glutathione metabolism but possesses L-cysteine as the principle low molecular weight thiol. L-Cysteine is essential for the structure, stability, and various protein functions, including catalysis, electron transfer, redox regulation, nitrogen fixation, and sensing for regulatory processes. Recently, we demonstrated that in E. histolytica, L-cysteine regulates various metabolic pathways including energy, amino acid, and phospholipid metabolism., Results: In this study, employing custom-made Affymetrix microarrays, we performed time course (3, 6, 12, 24, and 48 h) gene expression analysis upon L-cysteine deprivation. We identified that out of 9,327 genes represented on the array, 290 genes encoding proteins with functions in metabolism, signalling, DNA/RNA regulation, electron transport, stress response, membrane transport, vesicular trafficking/secretion, and cytoskeleton were differentially expressed (≥3 fold) at one or more time points upon L-cysteine deprivation. Approximately 60% of these modulated genes encoded proteins of no known function and annotated as hypothetical proteins. We also attempted further functional analysis of some of the most highly modulated genes by L-cysteine depletion., Conclusions: To our surprise, L-cysteine depletion caused only limited changes in the expression of genes involved in sulfur-containing amino acid metabolism and oxidative stress defense. In contrast, we observed significant changes in the expression of several genes encoding iron sulfur flavoproteins, a major facilitator super-family transporter, regulator of nonsense transcripts, NADPH-dependent oxido-reductase, short chain dehydrogenase, acetyltransferases, and various other genes involved in diverse cellular functions. This study represents the first genome-wide analysis of transcriptional changes induced by L-cysteine deprivation in protozoan parasites, and in eukaryotic organisms where L-cysteine represents the major intracellular thiol.

The present study was aimed at carrying out a cross-sectional copromicroscopic survey of helminths and intestinal protozoa in immigrants in Naples (southern Italy). Between October 2008 and November 2009, a total of 514 immigrants were tested comparing the FLOTAC dual technique and the ethyl acetate concentration technique. Combined results of the two techniques served as a diagnostic 'gold' standard and revealed an overall prevalence of parasitic infections of 61.9% (318/514). The ethyl acetate concentration technique detected a low number of positive results (49.0%) and this was confirmed for each helminth/protozoa species detected. Among helminths, Trichuris trichiura (3.9%), hookworms (3.7%) and Ascaris lumbricoides (1.4%) were the most prevalent. Strongyloides stercoralis (0.4%), Enterobius vermicularis (0.4%), Schistosoma mansoni (1.0%), Hymenolepis nana (1.6%) and Taenia spp. (0.2%) were also found, as well as zoonotic helminths, as Trichostrongylus spp. (0.8%) and Dicrocoelium dendriticum (0.8%). As regard to pathogenic protozoa, Blastocystis hominis was the most commonly detected (52.7%), followed by Entamoeba histolytica/Entamoeba dispar/Entamoeba moshkovskii (11.9%) and Giardia duodenalis (4.5%). Several issues concerning diagnosis, epidemiology and public health impact of parasitic infections in immigrants are offered for discussion. In conclusion, the present paper pointed out the need of better diagnosis and cure of the immigrant population in order to improve access to health care of this neglected and marginalised population group, for its own protection and care., (Copyright © 2010 Elsevier B.V. All rights reserved.)

Background & Aims: Colonic mucins secreted by goblet cells protect the colon by preventing the attachment of enteric pathogens to the epithelium. Entamoeba histolytica overcomes this protective barrier and causes ulcerations, allowing the parasite to disseminate to the liver and form abscesses. An in vitro model is used to study the interaction between E. histolytica and colonic mucins., Methods: Secretory mucins from the colonic adenocarcinoma cell line LS174T were collected and their functions assessed by their ability to inhibit amebic adherence to target cells and killing. The cytoprotective effect of mucus against E. histolytica cytolysis of LS174T monolayers was studied at 37 degrees C., Results: Sepharose 4B column chromatography, metabolic labeling with [3H]glucosamine, cesium chloride density gradient centrifugation, and amino acid and carbohydrate compositional analysis revealed that LS174T cell mucins were typical of native colonic mucins. Mucin O-linked oligosaccharides bound to and inhibited the adherence of amebae to Chinese hamster ovary cells. E. histolytica killing of Chinese hamster ovary cell monolayers occurred rapidly, whereas killing of LS174T monolayers with an intact mucus layer was significantly retarded., Conclusions: Our results show that colonic mucins serve as the first line of host defense against amebic invasion and provide a useful model to study pathogen-mucin interactions.

Uncomplicated amebic colitis is readily treated and has a mortality rate of less than 0.5%. Complications necessitating surgical intervention develop in only 6% to 11% of patients with symptomatic disease. However, the mortality rate in these patients ranges from 40% to 100% and stems in part from delays in diagnosis and treatment. Patients with known amebic colitis who show signs of systemic toxicity or of localized or generalized peritonitis are at high risk for complications; surgical consultation should be obtained. Patients who are thought to have acute appendicitis, diverticulitis, or obstructive or perforative carcinoma but have a history of dysentery atypical of that in these conditions should also be evaluated for amebiasis. Such patients should be treated presumptively until the diagnosis of amebic colitis can be excluded.

Amebiasis, a significant cause of morbidity and mortality on a global scale, is caused by invasion of the colonic mucosa by the cytolytic protozoan parasite Entamoeba histolytica. A review of the investigations into the mechanisms by which the parasite causes invasive disease is presented, including the relevant history, epidemiology, and pathology of amebiasis, the biology of the parasite, in vivo and in vitro studies of the pathogenesis of disease, the host immune responses, and possibilities for prevention and biologic control. New insights into the cell biology of E. histolytica, especially its adherence and cytolytic properties, offer several new approaches to biologic control of this invasive, destructive parasitic infection.

A parasitology surevy was conducted among inhabitants of 7 villages in 3 regencies in South Kalimantan Province, Indonesia. A total of 2,169 stool specimens, 2,756 blood smears and 1,027 serum specimens were obtained, representing samples from approximately 10%, 12% and 5% of the population, respectively. One to 8 different intestinal parasitic infections were detected in 97% of the people. Those parasites most frequently found were Trichuris trichiura (83%), Ascaris lumbricoides (79%), and hookworm (65%), followed by Entamoeba coli (37%), Endolimaxnana (12%), Entamoeba histolytica (12%), Iodamoeba bütschlii (11%), Giardia lamblia (5%), Entamoeba hartmanni (2%), Chilomastix mesnili (2%). Other parasites found were Enterobius vermicularis, Strongyloides stercoralis, Capillaria sp., Echinostoma sp., Hymenolepis diminuta, and Trichomonas hominis. Giardia lamblia was found more often in younger people and Entamoeba coli, Iodamoeba bütschlii and hookworm in the older age group. Ascaris lumbricoides occurred more frequently in females, and hookworm in males. Plasmodium vivax and Plasmodium falciparum were found in the blood smears of 4.4% of the people, mostly in the younger age groups. Seroepidemiological studies on amoebiasis were done by use of the indirect hemagglutination test with antigens prepared from the HK9 strain of Entamoeba histolytica maintained in axenic cultures. The frequency distribution of the reciprocal antibody titers showed a bimodal distribution with 34% of the population demonstrating positive reactions at titers of 1:128 or greater.

The present work was designed to investigate the capacity of trophozoites of Entamoeba histolytica to adhere to and digest human collagen types I and III in vitro. The time-course of binding of ameba to both human collagen types I and III was similar. However, the kinetics of detachment were different for each collagen type. Trophozoites of E. histolytica cultured on heat-reconstituted type I collagen gels produced a well-defined area of lysis. Quantitative studies using 14C-labeled collagen revealed that after 24 h of incubation, Entamoeba digested three and a half times more type I than type III collagen, thus suggesting the presence of a collagenase with higher specificity for type I collagen. This activity was optimum with trophozoites harvested after 42 h in culture (1.5 X 10(5) trophozoites/ml). The digestion of type I collagen was a function of the number of trophozoites, and was inhibited by EDTA, L-cysteine, and serum, but not by soybean trypsin inhibitor, phenylmethanesulfonyl fluoride, or N-ethylmaleimide (NEM). Electrophoretic analysis of the type I collagen fragments revealed three main classes of polypeptides of 75,000, 50,000, and 25,000 daltons. Subsequent proteolysis of these collagen fragments was probably carried out by other proteases derived from trophozoites. This activity was inhibited with 10 mM NEM. Collagenase activity appeared to be located at the plasma membrane and direct contact of the ameba with the substrate is required for collagen digestion. The results suggest that collagenase activity of E. histolytica may play an important role in tissue invasion.

We have attempted to determine whether amebal viruses are capable of viral conversion of the virulence of Entamoeba histolytical. Amebae of little or no virulence for the newborn hamster liver were infected with viruses obtained from four amebal strains of different virulence. Cultures of surviving amebae were increased in virulence by viruses from amebae of high, moderate, or low virulence, but decreased in virulence by the virus of the second most pathogenic amebal strain. Sequential infection with two viruses did not produce consistent cumulative effects on virulence. The changes in virulence noted are considered to be the unpredictable result of either selection pressures exerted by the lytic virus infection or possibly viral alterations of the amebae.

Results of histopathological examination of a solitary chronical amoebic abscess in the liver of a patient from Cambodia are described. The abscess was at a proliferously reparative phase and Entamoeba histolytica was detected at the border between the necrosis and inner wall of abscess, as well as in the proper non-specific granulation tissue of the inner layers of abscess capsule. A differential diagnosis of the amoebic abscess from similar parasitary or pseudoparasitary liver lesions and differential diagnosis of amoebae in histological sections are given. For orientation examinations of the liver tissue for the presence of amoebae the authors recommend the impregnation after Grocott and staining with Goldner's trichrome for a more detailed evaluation of histological sections.